The Hindu festival of Kumbh Mela, considered the largest human gathering on the planet, began in northern India on Monday with thousands of pilgrims flocking to the holy confluence of the Ganges, Yamuna and Sarasvati rivers.

Vast crowds of Hindu pilgrims in India bathed in sacred waters as the Kumbh Mela festival opened on Monday, with organisers expecting 400 million people -- the world's largest gathering of humanity -- to assemble over six weeks.India is the world's most populous nation, with 1.4 billion people, and so is used to large crowds.

India's Maha Kumbh Mela, or Great Pitcher Festival, is set to be the world's largest gathering of humanity, with 400 million visitors expected at the six-week event that began this week in the northern city of Prayagraj.

Millions of Hindu pilgrims are gathering in India to bathe in sacred waters for the six-week-long Kumbh Mela festival -- from the very old to babies, cave-dwelling monks to science teachers.The millennia-old Kumbh Mela,

Kumbh Mela, the world’s largest gathering, begins in India as millions bathe in the Ganges to seek spiritual salvation.

The Maha Kumbh Mela, or the Great Pitcher Festival, will bring more than 400 million people to Prayagraj city in northern India over a period of six weeks starting Monday, making it the largest gathering of humanity in the world.

Over about the next six weeks, Hindu pilgrims will gather at the confluence of three sacred rivers where they will take part in elaborate rituals.